1. Field of the Invention
The present invention relates to a color sheet having a light shielding effect, which is applied, as a film material or the like, to the roofs and exterior walls of buildings such as factories, residences, and the like, the roofs and exterior walls of carrying vehicles such as container cars, refrigeration vehicles, the roofs and exterior walls of ships, plants, storehouses, barns, and the like, and the covers and tents of military use and motorcars, whereby the temperature inside the buildings and so forth can be prevented from rising due to radiation of sunlight, and moreover, the designs and appearances can be improved.
2. Description of the Related Art
The roofs and exterior walls of building and structures are exposed to wind and rain and sunlight, and thus, are ready to be deteriorated. Accordingly, to prevent such deterioration of the roofs and exterior walls and improve the appearance thereof, ordinarily, they are protected by painting with coating materials. In recent years, to enhance the working-efficiency, the technique is carried out, in which color films or sheets suitable for their uses are formed in advance, and are set on the roofs and exterior walls. Thus, effects comparable to those of the above-described painting with coating materials can be simply obtained. In particular, buildings such as residences or the like are exposed to sunlight for a relatively long time. It is preferable to arrange the films or sheets, which effectively suppress from temperature rising inside the buildings especially in summer, onto the roofs and exterior walls of the buildings for improvement of the habitability thereof. Thus, the power consumption of air conditioners used for adjustment of the temperature can be reduced, and thus, the air conditioning cost can be reduced. Moreover, the use of the films or sheets is preferable from the viewpoint of global environments.
Moreover, with the recent distribution container trucks and refrigeration trucks for transporting goods in their low temperature state are generally used. To enhance the refrigerating and cooling effect of the container trucks and the refrigeration trucks, it has been desired to arrange films or sheets having a high heat-shielding property. Recently, it has been more required to give different colors to structures, vehicles, facilities and so forth for more aesthetical appearance, in addition to the high heat-shielding property required as described above.
Furthermore, tents are used outdoors as facilities for refuge and rescue at disaster, and are also used when armies and fire brigades are trained or their practical activities are carried out. However, problematically, on sunny days, the temperature inside the tents is increased, which hinders working or the like inside the tents. As countermeasures against this problem, large-scaled air conditioners are installed. However, it is difficult to decrease the temperature inside the tents, especially inside the large-sized tents and thus, the adjustment of the temperature is troublesome.
Techniques by which films or sheets having a heat shielding property are applied have been carried out for a long time. For example, Japanese Patent Application Laid-open No. Hei 8-81567 discloses a sheet containing an aluminum compound or a diimonium type compound in a specific amount based on a plastic resin so that the sheet has a heat shielding property. Japanese Patent Application Laid-open No. Hei 10-250002 discloses a sheet which is applied so as to be pitched outdoors, in which a layer containing inorganic oxide fine particles doped with a metal is formed on one side of a thermoplastic resin film, and furthermore, a layer containing hydrophilic inorganic colloidal particles is formed so that the heat-shielding property is enhanced. Moreover, Japanese Patent Application Laid-open No. 2002-12679 discloses a color film having heat-shielding property which is produced by mixing at least two type of pigments having a heat-shielding property with a thermoplastic resin film, and forming the mixture into a film.
Such sheets or films as disclosed in Japanese Patent Application Laid-open No. Hei 8-81567 and Japanese Patent Application Laid-open No. Hei 10-250002 are translucent and are suitable to be bonded to window glass sheets. However, the sheets or films are problems in that the heat-shielding properties thereof are not sufficiently high and a wide variety of colors can not be given.
Referring to such a sheet as described in Japanese Patent Application Laid-open No. 2002-12679, any optional color can be given to the sheet. However, since the sheet is composed of a single layer, the types of pigments which satisfy both of required colors and heat-shielding properties have a limitation. Thus, still more expensive pigments must be employed. Generally, for formation of thermoplastic resins, the resins are rolled by means of calendaring or are formed into sheets or films by means of extrusion. However, in the case of resins containing glass beads, problems will occur in that the glass beads are broken, so that the heat-shielding effect is decreased, and moreover, the rolls or the like of extruders are damaged, and so forth. Moreover, the films or sheets formed by calendaring or extrusion are oriented in the machining direction. Thus, the sheets or films tend to be curled due to heat which is applied during their processing. Thus, it is difficult to ensure the heat-shielding effect in many cases.
Moreover, the following light-shielding sheet is known in Japanese Patent Publication No. Hei 9-241979 (U.S. Pat. No. 3091685): the sheet comprises a base-fabric, a light-shielding layer and a surface layer, in which the light-shielding layer is laminated onto the base-fabric and is formed with a high polymer composition containing aluminum power paste and a black-color type colorant, and the surface layer is laminated onto the light-shielding layer and is formed with a high polymer composition. This light-shielding sheet, even if the thickness is smaller than that of a conventional light-shielding layer, can exhibit a higher light-shielding property than the conventional light-shielding layer. Moreover, the amount of the black-color type colorant to be added can be decreased. Thus, the light-shielding layer does not become excessively black, so that influences of the light-shielding layer exerted over the color of the surface layer can be reduced. However, it is very difficult to give a variety of colors to the sheet, since a black-color type colorant is used. To give various coloring, the sheet must be further improved.
Referring to a method for applying coating materials having a heat-shielding effect, the coating materials themselves to which functions of heat-shielding and the like are given are expensive compared to generally-used coating materials. Thus, the coating materials are not preferable from the viewpoint of economy. Thus, inexpensive means is desired. Moreover, in a case of applying coating materials having a heat-shielding effect, multi-layer coating is generally repeated to attain a large thickness. Thus, such coating-work takes much time and labor.